IC top/bottom surfaces coupled to test, scan, and comparator circuitry

ABSTRACT

A test control port (TCP) includes a state machine SM, an instruction register IR, data registers DRs, a gating circuit and a TDO MX. The SM inputs TCI signals and outputs control signals to the IR and to the DR. During instruction or data scans, the IR or DRs are enabled to input data from TDI and output data to the TDO MX and the top surface TDO signal. The bottom surface TCI inputs may be coupled to the top surface TCO signals via the gating circuit. The top surface TDI signal may be coupled to the bottom surface TDO signal via TDO MX. This allows concatenating or daisy-chaining the IR and DR of a TCP of a lower die with an IR and DR of a TCP of a die stacked on top of the lower die.

RELATED APPLICATIONS

This application is a divisional of prior application Ser. No.13/765,260, filed Feb. 12, 2013, now U.S. Pat. No. 8,977,919, issuedMar. 10, 2015;

Which claims priority from Provisional Application No. 61/654,207, filedJun. 1, 2012;

And also claims priority from Provisional Application No. 61/601,292,filed Feb. 21, 2012.

This disclosure is related to pending patent application TI-71343 whichis incorporated herein by reference.

FIELD OF DISCLOSURE

This disclosure relates to die that are designed to be used in a 3D diestack and in particular to a common test architecture designed into eachdie of the 3D die stack for accessing and testing digital circuits ofeach die using parallel scan techniques.

BACKGROUND OF THE DISCLOSURE

Die manufactured for use in a die stack must be tested at the waferlevel and then potentially retested after the die are singulated toensure only known good die are used in the stack. Each time an upper dieis stacked on top of a lower die that has been tested, the upper dieneeds to be retested to ensure it has not been damaged during thestacking process. Also, the interconnect between the lower and upper dieneeds to be tested and determined good. The interconnect between die ina 3D stack is provided by Through Silicon Vias (TSVs), which arevertical signaling paths between the bottom and top surfaces of eachdie. This testing process is repeated for each additional upper dieassembled onto the stack. It is therefore advantageous to have a commontest architecture in each die and a common method of accessing the testarchitecture in each die, independent of the stacked location of thedie.

BRIEF SUMMARY OF THE DISCLOSURE

The disclosure provides a test architecture for providing access to andcontrol of parallel scan paths within a single die or to parallel scanpaths in dies that are stacked.

DESCRIPTIONS OF THE VIEWS OF THE DISCLOSURE

FIG. 1 illustrates a die containing the test architecture of thedisclosure.

FIG. 2 illustrates a conventional parallel scan path arrangement thatcan be accessed and controlled by the test architecture of thedisclosure.

FIG. 3 illustrates a conventional parallel scan compression arrangementthat can be accessed and controlled by the test architecture of thedisclosure.

FIG. 4 illustrates a test circuit of the disclosure for eitheroutputting parallel test output data to a tester or comparing theparallel test output data to data input from a tester.

FIG. 5 illustrates a first example implementation of the comparator ofFIG. 4 of the disclosure.

FIG. 6 illustrates a second example implementation of the comparator ofFIG. 4 of the disclosure.

FIG. 7 illustrates a first example implementation of the test controlport (TCP) of the disclosure.

FIG. 8 illustrates a second example implementation of the TCP of thedisclosure.

FIG. 9 illustrates the test architecture in a die operating to inputparallel test input data to a parallel scan test circuit in the die andoutputting parallel test output data from the parallel test circuit,according to the disclosure.

FIG. 10 illustrates the test architecture operating to input paralleltest input data to a parallel test circuit and comparing the paralleltest output data with data input to the test circuit, according to thedisclosure.

FIG. 11 illustrates a stack die arrangement where the lower die istested as described in FIG. 9, according to the disclosure.

FIG. 12 illustrates a stack die arrangement where the lower die istested as described in FIG. 10, according to the disclosure.

FIG. 13 illustrates a stack die arrangement where the upper die istested as described in FIG. 9, via the lower die, according to thedisclosure.

FIG. 14 illustrates a stack die arrangement where the upper die istested as described in FIG. 10, via the lower die, according to thedisclosure.

FIG. 15 illustrates a stack die arrangement where the parallel scancircuits of the lower and upper die are daisy-chained together andtested as described in FIG. 9, according to the disclosure.

FIG. 16 illustrates a stack die arrangement where the parallel scancircuits of the lower and upper die are daisy-chained together andtested as described in FIG. 10, according to the disclosure.

FIG. 17 illustrates a die containing multiple selectable parallel scancircuits that may be tested as described in FIG. 9 or FIG. 10, accordingto the disclosure.

FIG. 18 illustrates the die of FIG. 17 further illustrating the TCP ofthe disclosure for clarity.

FIG. 19 illustrates an alternate implementation of the TCP of FIG. 7.

FIG. 20 illustrates the TCP of FIG. 19 were the state machine is an IEEEstandard 1149.1 Tap state machine.

FIG. 21 illustrates an alternate implementation of the TCP of FIG. 8.

FIG. 22 illustrates the TCP of FIG. 21 were the Test Control Inputs(TCI) inputs include IEEE standard 1500 signals.

FIG. 23 illustrates a die including the test architecture of thedisclosure where the Parallel Test Input (PTI) and Parallel Test Inputsand Outputs (PTIO) are shared for both test and functional signaling.

FIG. 24 illustrates the die of FIG. 23 where a multiplexer issubstituted for buffers “a” and “b”.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 illustrates a die 100 including the test architecture of thedisclosure. The bottom surface of the die includes signal contact points(micro bumps or metal pads) for a Parallel Test Input (PTI) bus 102, aTest Data input (TDI) 104, Test Control Inputs (TCI) 106, a Test DataOutput 108 and a Parallel Test Input/Output (PTIO) bus 110. The topsurface of the die includes signal contact points for a Parallel TestOutput (PTO) bus 112, TDO 114, Test Control Outputs (TCO) 116, TDI 118and a PTIO bus 120. The architecture includes a Test Control Port (TCP)122, a Test Circuit (TC) 124, at least one Parallel Scan Circuit 126 tobe tested, a first signal coupling means illustrated in this example assignal buffers “a” 128 and a second signal coupling means illustrated inthis example as signal buffers “b” 130. TCP is connected to the TDI, TCIand TDO bottom surface signals and the TDO, TCO and TDI top surfacesignals. TCP includes a control (CTL) output bus 131 that is connectedto the buffers, Parallel Scan Circuit and TC.

The Parallel Scan Circuit inputs PTI signals from the PTI bus 102 viaTSV signal connections 132 and outputs PTO signals to buffers “b” and tothe TC. The TC is connected to the PTIO bus TSV signal connections 134for outputting data onto the PTIO 110 bus or inputting data from thefrom the PTIO bus 120. The outputs of buffers “a” and “b” are connectedtogether and to the top surface PTO bus 112 via TSV signal connections136. If the top surface PTO bus 112 is to be driven from the bottom PTObus, buffers “a” are enabled by an enable 3 (E3) signal from the TCP CTLbus 131 and buffers “b” are disabled by enable 4 (E4) from the TCP CTLbus 131. If the top surface PTO bus 112 is to be driven by the PTOoutput 138 of the Parallel Scan Circuit, buffers “b” are enabled by E4and buffers “a” are disabled by E3.

While the first and second signal coupling means are shown to be buffers“a” 128 and “b” 130, the first and second coupling means could berealized using other types of circuitry such as but not limited to amultiplexer or transistor switches to allow the PTO bus 112 to be drivenby either the PTI bus 102 or by the PTO bus 138 output from the ParallelScan Circuit.

FIG. 2 illustrates one example implementation of the Parallel ScanCircuit 126 of FIG. 1. In this example, scan paths 202 input test datafrom PTI and output test data to PTO. The scan paths are controlled bythe CTL inputs from the TCP.

FIG. 3 illustrates another example implementation of the Parallel ScanCircuit 126 of FIG. 1. In this example, a decompressor (D) 302 inputscompressed test data from PTI and outputs decompressed test data toparallel scan paths 304, and a compactor (C) 306 inputs test data fromthe parallel scan paths and outputs compacted data on PTO. Thedecompressor, scan paths and compactor are controlled by the CTL inputsfrom the TCP.

While not shown in FIGS. 2 and 3, system clock inputs and associatedcircuitry may be used in conjunction with the TCP CTL signals to improvethe at-speed testing of the circuits, such as well known clock leakersystem clock circuits.

FIG. 4 illustrates an example implementation of the TC 124 of FIG. 1. Ina first mode of operation, the TC inputs PTO data 138 from the ParallelScan Circuit and outputs it to the PTIO bus 134, via 3-state buffers 4021-N. In a second mode of operation, the TC inputs PTO data from theParallel Scan Circuit and compares it to data input from the PTIO bus,using comparators (C) 404 1-N. The modes are controlled by enable (E1and E2) inputs from the CTL bus of the TCP. The comparators (C) havefail 405 1-N outputs that are set whenever a comparison failure occurs.The fail outputs are input to a gating circuit 406 that can detect whenone or more fail outputs are set to indicate a failure. The output ofthe gating circuit passes through a 3-state buffer 408 to a Compare FailOutput (CFO) 410 that is connected to a signal path in the PTIO bus. Thesecond mode of operation is advantageous at wafer probe since it enablesmultiple dies to be tested using a common PTI and PTIO bus from a testerto input test data to multiple die commonly connected to the PTI andPTIO buses.

FIG. 5 illustrates a first example comparator (C) 404 of FIG. 4 forcomparing PTO data to expected (EXP) data from the PTIO bus.

FIG. 6 illustrates a second example maskable comparator (C) 404 of FIG.4 for comparing PTO data to expected (EXP) data from the PTIO bus ormasking the compare operation off using mask (MSK) data input from thePTIO bus. When masked, the Fail signal output does not output a failureindication when a comparison fails.

FIG. 7 illustrates a first example implementation of the TCP 122 of FIG.1 which includes a state machine (SM) 702, an instruction register (IR)704, data registers (DRs) 706, a gating circuit 708 and a TDOmultiplexer (MX) 710. The SM inputs TCI signals 714 and outputsinstruction register control (IRC) signals to the IR and data registercontrol (DRC) signals to the DR. During instruction scans, the IR isenabled by IRC inputs to input data from TDI 712 and output data to theTDO multiplexer 710 and the top surface TDO signal 718. During datascans, a DR is enabled by the DRC inputs to input data from TDI 712 andoutput data to the TDO multiplexer 710 and the top surface TDO signal718.

The bottom surface TCI inputs 714 may be coupled to the top surface TCOsignals 720 via the gating circuit 708. The top surface TDI signal 722may be coupled to the bottom surface TDO signal 716 via TDO multiplexer710. This allows concatenating or daisy-chaining the IR and DR of a TCPof a lower die with an IR and DR of a TCP of a die stacked on top of thelower die. The instruction register outputs (IRO) include an enable(ENA) signal for the gating circuit 708 and a second select (SEL) signalfor TDO multiplexer 710. The CTL bus output from the TCP includes IROsignals and DRC signals. The gating circuit 708 may gate one, more thanone or all of the TCI signals. Non-gated TCI signals are coupled toappropriate top surface TCO signals, as shown in dotted line. The SM,IR, and DRs of this implementation could be the TAP SM, IR and DRs asdefined in the IEEE 1149.1 boundary scan standard.

FIG. 8 illustrates a second example implementation 800 of the TCP 122 ofFIG. 1. This implementation is identical to the FIG. 7 implementationwith the exception that it does not include a SM 702. The TCI inputs 802are coupled to the IRC inputs of IR 704 and DRC inputs of DR 706. Duringinstruction scans, the IR is enabled by the IRC signals from the TCIinputs 802 to input data from TDI 712 and output data to the TDOmultiplexer 710 and the top surface TDO signal 718. During data scans, aDR is enabled by DRC signals from the TCI inputs 802 to input data fromTDI 712 and output data to the TDO multiplexer 710 and the top surfaceTDO signal 718.

The bottom surface TCI inputs 802 may be coupled to the top surface TCOsignals 720 via the gating circuit 708. The top surface TDI signal 722may be coupled to the bottom surface TDO signal 716 via the TDOmultiplexer 710. This allows concatenating or daisy-chaining the IR andDR of a TCP 122 of a lower die with an IR and DR of a TCP 122 of a diestacked on top of the lower die. The instruction register outputs (IRO)include an enable (ENA) signal for the gating 708 circuit and the SELsignal to TDO multiplexer 710. The CTL bus output 724 from the TCPincludes IRO signals and DRC signals. The gating circuit 708 may gateone, more than one or all of the TCI signals. Non-gated TCI signals arecoupled to appropriate top surface TCO signals, as shown in dotted line.The TCI input bus 802, IR 704 and DRs 706 of this implementation couldbe the control inputs, IR and DRs as defined in IEEE 1500 core wrappertest standard.

FIG. 9 illustrates the die test architecture of FIG. 1 when aninstruction has been loaded into the TCP's IR to enable the ParallelScan Circuit to be tested by inputting PTI data from the PTI bus 102 andoutputting PTO data to the PTIO bus 110, as seen in darkened line. TheCTL outputs 131 from the TCP 122 controls the capture and input andoutput shift operations of Parallel Scan Circuit 126 during test.

FIG. 10 illustrates the die test architecture of FIG. 1 when aninstruction has been loaded into the TCP's IR to enable the ParallelScan Circuit 126 to be tested by inputting PTI data from the PTI bus 102and comparing the PTO output data from the Parallel Scan Path 126 withdata input from the PTIO bus 110, as seen in darkened line. The CTLoutputs from the TCP 122 controls the capture and input and output shiftoperations of Parallel Scan Circuit 126 during test. During this test,the CFO output 410 (dotted line) of the TC 124 of FIG. 4 is enabled tooutput comparison failures on the PTIO bus 110.

FIG. 11 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, the Parallel Scan Circuit 126 of the bottom die 100 is beingtested as described in FIG. 9. The IR of the TCP 1122 of the top die hasbeen loaded with an instruction which place the top die in a quiescentmode that ignores the testing of the bottom die, does not interfere withthe testing of the bottom die and disables the tri-state buffers of TC1124 of the top die. The TCO outputs 116 from the bottom die to the TCIinputs 1106 of the top die will typically be gated off during testing ofthe bottom die.

FIG. 12 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, the Parallel Scan Circuit 126 of the bottom die 100 is beingtested as described in FIG. 10. The IR of the TCP 1122 of the top die1102 has been loaded with an instruction which places the top die in aquiescent mode that ignores the testing of the bottom die, does notinterfere with the testing of the bottom die and disables the tri-statebuffers of TC 1124 of the top die. The TCO outputs 116 from the bottomdie to the TCI inputs 1106 of the top die will typically be gated offduring testing of the bottom die.

FIG. 13 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, the Parallel Scan Circuit 1126 of the top die 1102 is beingtested as described in FIG. 9. The IR of the TCP 122 of the bottom die100 has been loaded with an instruction which place the bottom die 100in a quiescent mode that ignores the testing of the top die 1102, doesnot interfere with the testing of the top die, disables the tri-statebuffers of TC 124 of the bottom die and enables buffers “a” 128 to passthe PTI signals up to the top die. The TCO outputs from the bottom die116 to the top die 1106 will be gated on during testing of the top dieto control the top die's TCP 1122.

FIG. 14 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, the Parallel Scan Circuit 1126 of the top die 1102 is beingtested as described in FIG. 10. The IR of the TCP 122 of the bottom die100 has been loaded with an instruction which place the bottom die in aquiescent mode that ignores the testing of the top die, does notinterfere with the testing of the top die, disables the tri-statebuffers of TC 124 of the bottom die and enables buffers “a” 128 to passthe PTI signals up to the top die. The TCO outputs from the bottom die116 to the top die 1106 will be gated on during testing of the top dieto control the top die's TCP 1122.

FIG. 15 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, instructions have been loaded into the IRs of the TCPs 122,1122 of the bottom and top die to daisy-chain the Parallel Scan Circuits126, 1126 of the bottom and top die together to form a PTI to PTO paththrough both Parallel Scan Circuits, from the PTI 102 of the bottom dieto the PTIO 110 of the bottom die. The instruction loaded in the bottomdie TCP 122 enables buffers “b” 130 to drive the PTI inputs to the topdie, disables the tri-state buffers of TC 124 of the bottom die andgates on the TCO outputs 116 to the TCI inputs 1116 of the top die. Theinstruction in the TCP of the top die enables the tri-state buffers ofTC 1124 of the top die to drive the PTIO bus 1134, 134, 110.

FIG. 16 illustrates a stack 1100 including a bottom die 100 and a topdie 1102, both including the die test architecture of FIG. 1. In thisexample, instructions have been loaded into the IRs of the TCPs 122,1122 of the bottom and top die to daisy-chain the Parallel Scan Circuits126, 1126 of the bottom and top die together to form a PTI to PTO paththrough both Parallel Scan Circuits, from the PTI 102 of the bottom dieto the PTO inputs to TC 1124 of the top die. The instruction loaded inthe bottom die TCP 122 enables buffers “b” 130 to drive the PTI inputsto the top die, disables the tri-state buffers of TC 124 of the bottomdie and gates on the TCO 116 outputs to the TCI inputs 1106 of the topdie. The instruction in the TCP 1122 of the top die disables thetri-state buffers of TC 1124 of the top die so that data from PTIO 110can be input to the comparators of TC 1124 to compare against the PTOdata being input to the comparator from the Parallel Scan Circuit 1126of the top die.

While the stack die examples of FIGS. 11-16 show only two dies includingthe test architecture of the disclosure in the stack, the stack couldcontain any number of stacked dies including the test architecture ofthe disclosure.

While in the preceding Figure examples, only one Parallel Scan Circuit126 was shown in a die, any number of Parallel Scan Circuits may beincluded in a die and tested using the test architecture of thedisclosure. FIG. 17 below shows one preferred way of accessing pluralParallel Scan Circuits in a die.

FIG. 17 illustrates multiple Parallel Scan Circuits 126 a, 126 b in adie 1700 outputting their PTO outputs to a multiplexer 1702. The PTOoutputs of the Parallel Scan Circuit to be tested are selected by themultiplexer 1702 to be output on the PTO bus to the TC 124 and to theinputs of buffers “b” 130. Multiplexer 1702 is controlled by PTO select(PTOSEL) signals from the IRO part of the CTL bus of the TCP 122. Themultiplexer 1702 allows multiple Parallel Scan Circuits to share acommon TC 124, which reduces test circuit overhead in the die 100.

FIG. 18 is the same as FIG. 17 but it includes the TCP 1822 to moreclearly illustrate the TCP CTL outputs being connected buffers “a” 128and “b” 130, Parallel Scan Circuits 126 a, 126 b, multiplexer 1702 andTC 124.

FIG. 19 illustrates a third example implementation of the TCP 122 ofFIG. 1, similar to the first example implementation of FIG. 7. Thisthird example implementation TCP 1900 includes a state machine (SM) 702,an instruction register (IR) 704, data registers (DRs) 706, a gatingcircuit 708, first TDO multiplexer (MX) 712 and a second TDO multiplexer(MX) 710. The SM inputs TCI signals and outputs instruction registercontrol (IRC) signals to the IR, data register control (DRC) signals tothe DR and a first select (SEL) signal to the first multiplexer 712.During instruction scans, the IR inputs data from TDI and outputs datato the TDO multiplexer 710 and the top surface TDO signal 718, via TDOmultiplexer 712. During data scans, a DR inputs data from TDI andoutputs data to the TDO multiplexer 710 and the top surface TDO signal718, via TDO multiplexer 712.

The bottom surface TCI inputs 714 may be coupled to the top surface TCOsignals 720 via the gating circuit 708. The top surface TDI signal 722may be coupled to the bottom surface TDO signal 716 via TDO multiplexer710. This allows concatenating or daisy-chaining the IR and DR of a TCPof a lower die with an IR and DR of a TCP of a die stacked on top of thelower die. The instruction register outputs (IRO) include an enable(ENA) signal for the gating circuit and a second select (SEL) signal forTDO multiplexer 710. The CTL bus output from the TCP includes IROsignals and DRC signals. The gating circuit 708 may gate one, more thanone or all of the TCI signals. Non-gated TCI signals are coupled toappropriate top surface TCO signals, as shown in dotted line. The SM,IR, and DRs of this implementation could be the TAP SM, IR and DRs asdefined in the IEEE 1149.1 boundary scan standard.

FIG. 20 illustrates the TCP 2000 of FIG. 19 where the SM 702 is realizedas an IEEE standard 1149.1 Tap State Machine (TSM) 2002. The TCI inputs714 to the TSM 2002 include a test clock (TCK) 2004 and test mode select(TMS) signal 2006. The gating circuit 708 may gate the TMS signal, theTCK signal or both the TMS and TCK signals. Non-gated TCI signals arecoupled to appropriate top surface TCO signals, as shown in dotted line.

FIG. 21 illustrates a fourth example implementation 2100 of the TCP 122of FIG. 1. This implementation is identical to the FIG. 19implementation with the exception that it does not include a SM 122. TheTCI inputs are coupled to the IRC inputs of IR 704, the DRC inputs ofDRs 706 and SEL input of TDO multiplexer 712. During instruction scans,the IR is controlled by IRC signals from the TCI inputs to input datafrom TDI 712 and output data to the TDO multiplexer 710 and the topsurface TDO signal 718, via TDO multiplexer 712. During data scans, a DRis controlled by the DRC signals from the TCI inputs 714 to input datafrom TDI 712 and output data to the TDO multiplexer 710 and the topsurface TDO signal 718, via TDO multiplexer 712.

The bottom surface TCI inputs 714 may be coupled to the top surface TCOsignals 720 via the gating circuit 708. The top surface TDI signal 722may be coupled to the bottom surface TDO signal 716 via the TDOmultiplexer 710. This allows concatenating or daisy-chaining the IR andDR of a TCP of a lower die with an IR and DR of a TCP of a die stackedon top of the lower die. The instruction register outputs (IRO) includean enable (ENA) signal for the gating circuit and the SEL signal to TDOmultiplexer 710. The CTL bus output from the TCP includes IRO signalsand DRC signals. The gating circuit 708 may gate one, more than one orall of the TCI signals. Non-gated TCI are coupled to appropriate topsurface TCO signals, as shown in dotted line. The TCI input bus 714, IRand DRs of this implementation could be the control inputs, IR and DRsas defined in IEEE 1500 core wrapper test standard.

FIG. 22 illustrates the TCP 2200 of FIG. 21 where the TCI inputs 714 aredefined to be the wrapper control input signals defined in IEEE standard1500, which includes a wrapper clock (WRCK) signal, select wrapperinstruction register (SelectWIR) signal, shift wrapper (ShiftWR) signal,capture wrapper (CaptureWR) signal, update wrapper (UpdateWR) signal andreset wrapper (ResetWR) signal. The wrapper instruction register (WIR)2202 is the same as the IR of FIG. 8, it is just labeled WIR by IEEE1500. The gating circuit 708 may gate one, more than one or all of theTCI signals. Non-gated TCI signals a coupled to appropriate top surfaceTCO signals, as shown in dotted line.

FIG. 23 illustrates a die 2302 including the test architecture of thedisclosure. Die 2302 differs from die 100 of FIG. 1 as follows; (1) thePTI TSVs 132 are shared between inputting PTI signals 102 to the testarchitecture and inputting functional data input (FDI) signals 2310 tofunctional circuitry (FC) 2304 of the die, (2) the PTO TSVs 136 areshared between outputting PTO signals 112 from the test architecture andoutputting function data output (FDO) signals 2312 from the FC 2304 and(3) the PTIO TSVs 134 are shared between inputting or outputting PTIO110, 120 signals to the test architecture and inputting or outputtingfunctional data input/output (FDIO) signals 2314, 2316 to functionalcircuitry (FC) 2306 of the die. When the die is in functional mode, aninstruction in the TCP 122 will disable buffers “a” 128 and “b” 130 anddisable the buffers in the TC 124.

In functional mode, FDI can be input to FC 2304 via TSVs 132, FDO can beoutput from FC 2304 via TSVs 136 and FDIO can be input and output to FC2006 via TSVs 134. When the die is in test mode, an instruction in theTCP 122 will disable the outputs of FC 2004 and 2006 using an enablesignal (E5) from the CTL output of TCP 122. In test mode, PTI can beinput to the test architecture via TSVs 132, PTO can be output from thetest architecture via TSVs 136 and PTIO can be input to or output fromthe test architecture via TSVs 134, as previously described.

FIG. 24 illustrates a die 2402 include the test architecture of thedisclosure. The only difference between the die 2302 of FIG. 23 and die2402 of FIG. 24 is that a 3-state multiplexer 2404 is shown being usedin die 2402 in place of buffers “a” and “b”. The E3 input to themultiplexer selects either PTI data from TSVs 132 or the PTO data fromthe Parallel Scan Circuit to be output to TSVs 136. The E4 input to themultiplexer enables or disables the multiplexer outputs to TSVs 136. Themultiplexer operates the same as the buffers “a” and “b” described inFIG. 23.

In this disclosure the words connected and coupled both mean a “link”formed between elements mentioned in this disclosure. The elements couldbe, but are not limited to circuits, buses and contact points. The linksmay be direct links such as links formed between two elements by a wireor they may be indirect links such as a links formed between elementsthrough intermediate circuitry, registered circuitry or bufferedcircuitry for example.

The invention claimed is:
 1. An integrated circuit die comprising: A. afirst surface having parallel test input contacts, a test data inputcontact, test control input contacts, a test data output contact, andparallel test input and output contacts; B. a second surface oppositethe first surface, the second surface having parallel test outputcontacts, a test data output contact, test control output contacts, atest data input contact, and parallel test input and output contacts; C.a test control port having leads coupled to the first surface test datainput, test control input, and test data output contacts, to the secondsurface test data output, test control output, and test data inputcontacts, and having control outputs; D. parallel scan circuitry havingparallel test inputs coupled to the second surface parallel test inputcontacts, a control input coupled to a control output of the testcontrol port and parallel test outputs; E. comparator circuitry havinginputs coupled to the parallel test outputs of the parallel scancircuitry, input and output leads coupled to the parallel test input andoutput contact points of the first and second surfaces, a control inputconnected to a control output of the test control port, and a failoutput; F. first coupling circuitry having inputs coupled to theparallel test outputs of the parallel scan circuitry, a control inputcoupled to a control output of the test control port, and outputscoupled to the parallel test output contacts of the second surface; andG. second coupling circuitry having inputs coupled to the parallel testinput contacts of the first surface, a control input coupled to acontrol output of the test control port, and outputs coupled to theparallel test output contacts of the second surface.
 2. The integratedcircuit die of claim 1 in which the first coupling circuitry includestri-state buffers and the second coupling circuitry includes tri-statebuffers.